Arsenal's title challenge suffered a blow as their late rally was only enough to secure a draw at West Brom.
Albion were 2-0 up just before the hour mark when Peter Odemwingie capitalised on a mix-up between Manuel Almunia and Sebastien Squillaci to add to Steven Reid's early header.
The Gunners staged a comeback with goals in the 70th minute from Andrey Arshavin and 78th from Robin van Persie, but they could not find a winner and are now five points behind Barclays Premier League leaders Manchester United, who beat Bolton 1-0.
The Baggies, meanwhile, are a point above the relegation zone in 16th place as they were at the start of the day.
Arsene Wenger's team were in need of a lift following their Carling Cup final defeat and elimination from the Champions League and FA Cup over the last few weeks, but they made the worst possible start as West Brom took the lead after only three minutes.
Albion skipper Chris Brunt swung in a corner and Reid was allowed the space to jump and crash a header beyond Almunia for his first Premier League goal for nearly five years.
Aaron Ramsey - who was starting a game for the Gunners for the first time since breaking his leg last season - appeared to be the main culprit in failing to mark Reid as Arsenal's defensive frailties were laid bare.
Moments later Jerome Thomas won the ball and broke forward, sending in a dangerous delivery that just evaded Odemwingie.
The visitors started to gain more possession but were struggling to get a proper foothold and the game was temporarily halted after 20 minutes when Laurent Koscielny clashed heads with James Morrison, the latter having to come off for treatment.
While Morrison was off the pitch Arsenal showed some threatening signs, with only the head of Jonas Olsson preventing Ramsey getting on the end of a Gael Clichy cross.
Arsenal should have then equalised when Van Persie's header came back off the bar.
The ball dropped to Ramsey right in front of goal, but the Wales midfielder could only strike it straight at Scott Carson.
As Morrison returned with a bandage around his head the Gunners continued to press, Samir Nasri seeing a cross come off the legs of Abdoulaye Meite towards goal but Carson was able to avert the danger.
